Aqueous liquid compositions, for example hand dishwashing compositions, generally need to have a specified viscosity behavior to be acceptable to the consumer. Many liquid compositions should have a viscosity behavior which provides pourability and ease of dissolution in water in order to be considered consumer acceptable, particularly in liquid cleaning products like hand dishwashing liquid. For hand dishwashing compositions the dissolution rate of the liquid in water is desired to be rapid so that foam generation is not delayed, since foam is a signal to consumers that the detergent is high quality. Pourability and dissolution are in part linked to liquid viscosity.
A variety of different viscosity control agents are conventionally used in such compositions.
Ethanol is known for uses as a viscosity controller in aqueous hand dishwashing liquid compositions, even though the ethanol does not contribute to enhanced dishwashing performance. However, in order to provide the required viscosity control, ethanol tends to be used at high concentrations. For example ethanol comprises 6.5 weight % of the total composition in one known aqueous hand dishwashing liquid composition. Such high ethanol compositions may have the desired viscosity profile, but may form an undesired gel phase at temperatures below 0° C., for example at a temperature of −4° C. or lower, causing an evident phase separation at the bottom of a bottle containing the composition. This is undesirable for the consumer. Also, the high ethanol content increases the cost of the composition. For example, a 6.5 weight % ethanol content may represent about 12% of the cost of the aqueous hand dishwashing liquid composition.
There is a need in the art for aqueous liquid compositions, for example hand dishwashing compositions, which can incorporate a viscosity modifier system to provide a viscosity behavior which is acceptable to the consumer yet avoids the gel phase formation and high ethanol cost of known ethanol-containing formulations.
Therefore, it would be desirable to provide an aqueous liquid composition, for example a hand dishwashing composition, which can provide the combination of a desired viscosity behavior, good anti-gelling performance at sub-zero temperatures and an acceptable production cost.